Research On Content Propagation Delay In Mobile Opportunistic Networks

With the continuous development of wireless network technology and in-depth study of actual scenarios,it is found that under certain special network environments or real-world scenarios,due to the limitations of geographical location or infrastructure construction,the network cannot be fully connected.Which leads to the inability of traditional network communication methods for data transmission.However,the opportunistic communication created by the mobile opportunistic network using the mobility of the node can satisfy the data transmission between the nodes under the non-fully connected state network.But,the development of mobile opportunistic networks in data forwarding and caching strategies still faces some challenges,such as ignoring the impact of node sociality on the incentive process,resulting in poor network performance.Different factors are used to evaluate the similarity between nodes,but the importance of nodes is ignored,which has a great impact on the performance of the system.Based on the above problems,this paper studies the content propagation delay in the mobile opportunistic network based on the related research.Mainly from the two aspects of data distribution and caching strategy,the relevant contributions are as follows:(1)From the perspective of opportunistic caching and opportunistic forwarding,the dynamics of crowd participation are studied,and how to use these opportunities to effectively allocate content caching and data forwarding is discussed.The opportunistic cache is discussed first from the perspective of cache size,number of cache copies,and content allocation scheme.Secondly,we study the transmission of opportunities from the perspective of control and data planes,so that there are more effective programs to encourage more people to participate in data forwarding.(2)The performance of a mobile opportunistic network mainly depends on the cooperation between nodes.So far,researchers have neglected the impact of node sociality on the incentive process,resulting in poor network performance.This paper proposes the FollowMe collaboration scheme,which combines the social importance of nodes with evolutionary game theory to improve the cooperative behavior of nodes.First,the prisoner dilemma model is used to establish the game income matrix between nodes.Second,we introduce signal references as a game rule between nodes.The number of nodes in different strategies is selected in a round of games,and the probability formula is used to calculate the cumulative benefit of the nodes.Finally,use the Fermi function to determine if the node updates the policy.This strategy can promote the cooperative behavior between nodes and improve the transmission rate of data packets.(3)Considering that previous studies used different factors to evaluate the similarity between nodes,the importance of nodes however was ignored.A distributed routing algorithm called SSR using social importance to compute node similarity is proposed.First,the node records the social importance of meeting other nodes in its buffer.Second,when two nodes are in contact,a dynamic time warping(DTW)algorithm is used to calculate the similarity of the social importance sequences of the two nodes.The more similar the two sequences are,the more similar the social behavior of the two nodes is.Finally,the data packet is always forwarded to the relay node with the highest similar social behavior to the destination node to ensure transmission efficiency.(4)On the basis of the above,from the perspective of mobile opportunistic network data offloading,it is studied how to offload the content to the small base station in advance to minimize the transmission delay of the entire cache system.A data offloading scheme based on delay gain is proposed.In the environment with limited node buffer,the lagrange multiplier method and KKT condition analysis method are used to optimize the message transmission delay,and select the maximum gain of the delay store data packets to dynamically resolve what message should be allocated to which nodes so that the propagation delay better.Based on the above problems,this paper mainly starts from the two aspects of data distribution and caching strategy,motivates the nodes to participate more in the routing,and improves the routing and caching mechanism to achieve an optimal content transmission delay.